<template>
    <view
        class="u-subsection"
        ref="u-subsection"
        :class="[`u-subsection--${mode}`]"
        :style="[addStyle(customStyle), wrapperStyle]"
    >
        <view
            class="u-subsection__bar cursor-pointer"
            ref="u-subsection__bar"
            :style="[barStyle]"
            :class="[
                mode === 'button' && 'u-subsection--button__bar',
                innerCurrent === 0 && mode === 'subsection' && 'u-subsection__bar--first',
                innerCurrent > 0 &&
                    innerCurrent < list.length - 1 &&
                    mode === 'subsection' &&
                    'u-subsection__bar--center',
                innerCurrent === list.length - 1 &&
                    mode === 'subsection' &&
                    'u-subsection__bar--last'
            ]"
        ></view>
        <view
            class="u-subsection__item cursor-pointer"
            :class="[
                `u-subsection__item--${index}`,
                index < list.length - 1 && 'u-subsection__item--no-border-right',
                index === 0 && 'u-subsection__item--first',
                index === list.length - 1 && 'u-subsection__item--last'
            ]"
            :ref="`u-subsection__item--${index}`"
            :style="[itemStyle(index)]"
            @tap="clickHandler(index)"
            v-for="(item, index) in list"
            :key="index"
        >
            <text class="u-subsection__item__text" :style="[textStyle(index)]">{{
                getText(item)
            }}</text>
        </view>
    </view>
</template>

<script>
// #ifdef APP-NVUE
const dom = uni.requireNativePlugin('dom')
const animation = uni.requireNativePlugin('animation')
// #endif
import { props } from './props.js'
import { mpMixin } from '../../libs/mixin/mpMixin'
import { mixin } from '../../libs/mixin/mixin'
import { addStyle, addUnit, sleep } from '../../libs/function/index'
/**
 * Subsection 分段器
 * @description 该分段器一般用于用户从几个选项中选择某一个的场景
 * @tutorial https://ijry.github.io/uview-plus/components/subsection.html
 * @property {Array}			list			tab的数据
 * @property {String ｜ Number}	current			当前活动的tab的index（默认 0 ）
 * @property {String}			activeColor		激活时的颜色（默认 '#da8c10' ）
 * @property {String}			inactiveColor	未激活时的颜色（默认 '#303133' ）
 * @property {String}			mode			模式选择，mode=button为按钮形式，mode=subsection时为分段模式（默认 'button' ）
 * @property {String ｜ Number}	fontSize		字体大小，单位px（默认 12 ）
 * @property {Boolean}			bold			激活选项的字体是否加粗（默认 true ）
 * @property {String}			bgColor			组件背景颜色，mode为button时有效（默认 '#eeeeef' ）
 * @property {Object}			customStyle		定义需要用到的外部样式
 * @property {String}	        keyName	        从`list`元素对象中读取的键名（默认 'name' ）
 *
 * @event {Function} change		分段器选项发生改变时触发  回调 index：选项的index索引值，从0开始
 * @example <u-subsection :list="list" :current="curNow" @change="sectionChange"></u-subsection>
 */
export default {
    name: 'u-subsection',
    mixins: [mpMixin, mixin, props],
    data() {
        return {
            // 组件尺寸
            itemRect: {
                width: 0,
                height: 0
            },
            innerCurrent: '',
            windowResizeCallback: {}
        }
    },
    watch: {
        list(newValue, oldValue) {
            this.init()
        },
        current: {
            immediate: true,
            handler(n) {
                if (n !== this.innerCurrent) {
                    this.innerCurrent = n
                }
                // #ifdef APP-NVUE
                // 在安卓nvue上，如果通过translateX进行位移，到最后一个时，会导致右侧无法绘制圆角
                // 故用animation模块进行位移
                const ref = this.$refs?.['u-subsection__bar']?.ref
                // 不存在ref的时候(理解为第一次初始化时，需要渲染dom，进行一定延时再获取ref)，这里的100ms是经过测试得出的结果(某些安卓需要延时久一点)，勿随意修改
                sleep(ref ? 0 : 100).then(() => {
                    animation.transition(this.$refs['u-subsection__bar'].ref, {
                        styles: {
                            transform: `translateX(${n * this.itemRect.width}px)`,
                            transformOrigin: 'center center'
                        },
                        duration: 300
                    })
                })
                // #endif
            }
        }
    },
    computed: {
        wrapperStyle() {
            const style = {}
            // button模式时，设置背景色
            if (this.mode === 'button') {
                style.backgroundColor = this.bgColor
            }
            return style
        },
        // 滑块的样式
        barStyle() {
            const style = {}
            style.width = `${this.itemRect.width}px`
            style.height = `${this.itemRect.height}px`
            // 通过translateX移动滑块，其移动的距离为索引*item的宽度
            // #ifndef APP-NVUE
            style.transform = `translateX(${this.innerCurrent * this.itemRect.width}px)`
            // #endif
            if (this.mode === 'subsection') {
                // 在subsection模式下，需要动态设置滑块的圆角，因为移动滑块使用的是translateX，无法通过父元素设置overflow: hidden隐藏滑块的直角
                style.backgroundColor = this.activeColor
            }
            return style
        },
        // 分段器item的样式
        itemStyle(index) {
            return index => {
                const style = {}
                if (this.mode === 'subsection') {
                    // 设置border的样式
                    style.borderColor = this.activeColor
                    style.borderWidth = '1px'
                    style.borderStyle = 'solid'
                }
                return style
            }
        },
        // 分段器文字颜色
        textStyle(index) {
            return index => {
                const style = {}
                style.fontWeight = this.bold && this.innerCurrent === index ? 'bold' : 'normal'
                style.fontSize = addUnit(this.fontSize)
                // subsection模式下，激活时默认为白色的文字
                if (this.mode === 'subsection') {
                    style.color = this.innerCurrent === index ? '#fff' : this.inactiveColor
                } else {
                    // button模式下，激活时文字颜色默认为activeColor
                    style.color =
                        this.innerCurrent === index ? this.activeColor : this.inactiveColor
                }
                return style
            }
        }
    },
    mounted() {
        this.init()
        this.windowResizeCallback = res => {
            this.init()
        }
        uni.onWindowResize(this.windowResizeCallback)
    },
    beforeUnmount() {
        uni.offWindowResize(this.windowResizeCallback)
    },
    emits: ['change'],
    methods: {
        addStyle,
        init() {
            this.innerCurrent = this.current
            sleep().then(() => this.getRect())
        },
        // 判断展示文本
        getText(item) {
            return typeof item === 'object' ? item[this.keyName] : item
        },
        // 获取组件的尺寸
        getRect() {
            // #ifndef APP-NVUE
            this.$uGetRect('.u-subsection__item--0').then(size => {
                this.itemRect = size
            })
            // #endif

            // #ifdef APP-NVUE
            const ref = this.$refs['u-subsection__item--0'][0]
            ref &&
                dom.getComponentRect(ref, res => {
                    this.itemRect = res.size
                })
            // #endif
        },
        clickHandler(index) {
            this.innerCurrent = index
            this.$emit('change', index)
        }
    }
}
</script>

<style lang="scss" scoped>
@import '../../libs/css/components.scss';

.u-subsection {
    @include flex;
    position: relative;
    overflow: hidden;
    /* #ifndef APP-NVUE */
    width: 100%;
    box-sizing: border-box;
    /* #endif */

    &--button {
        height: 34px;
        background-color: rgb(238, 238, 239);
        padding: 3px;
        border-radius: 4px;
        align-items: stretch;

        &__bar {
            background-color: #ffffff;
            border-radius: 4px !important;
        }
    }

    &--subsection {
        height: 32px;
    }

    &__bar {
        position: absolute;
        /* #ifndef APP-NVUE */
        transition-property: transform, color;
        transition-duration: 0.3s;
        transition-timing-function: ease-in-out;
        /* #endif */

        &--first {
            border-top-left-radius: 4px;
            border-bottom-left-radius: 4px;
            border-top-right-radius: 0px;
            border-bottom-right-radius: 0px;
        }

        &--center {
            border-top-left-radius: 0px;
            border-bottom-left-radius: 0px;
            border-top-right-radius: 0px;
            border-bottom-right-radius: 0px;
        }

        &--last {
            border-top-left-radius: 0px;
            border-bottom-left-radius: 0px;
            border-top-right-radius: 4px;
            border-bottom-right-radius: 4px;
        }
    }

    &__item {
        @include flex;
        flex: 1;
        justify-content: center;
        align-items: center;
        // vue环境下，需要设置相对定位，因为滑块为绝对定位，item需要在滑块的上面
        position: relative;

        &--no-border-right {
            border-right-width: 0 !important;
        }

        &--first {
            border-top-left-radius: 4px;
            border-bottom-left-radius: 4px;
        }

        &--last {
            border-top-right-radius: 4px;
            border-bottom-right-radius: 4px;
        }

        &__text {
            font-size: 12px;
            line-height: 14px;
            @include flex;
            align-items: center;
            transition-property: color;
            transition-duration: 0.3s;
        }
    }
}
</style>
